What are fossils? What do they tell us a | Class 10 Science Chapter Heredity and Evolution, Heredity and Evolution NCERT Solutions

A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw

Differentiate between inherited and acquired characters. Give one example for each type.

How is the sex of the child determined in human beings?

How do Mendel’s experiments show that traits are inherited independently?

What evidence do we have for the origin of life from inanimate matter?

Why did Mendel choose pea plant for his experiments?

Explain the terms analogous and homologous organs with examples.

In the following crosses write the characteristics of the progeny

What factors could lead to the rise of a new species?

How are the areas of study – evolution and classification – interlinked?

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

Draw the structure for the following compounds.                

       (i)    Ethanoic acid             (ii)   Bromopentane*
       (iii)  Butanone                   (iv)   Hexanal.

*Are structural isomers possible for bromopentane?

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

(a)  What property do all elements in the same column of the Periodic Table as boron have in common?
(b)  What property do all elements in the same column of the Periodic Table as fluorine have in common?

Calculate the number of electrons constituting one coulomb of charge.

What is an homologous series? Explain with an example.

Why is variation beneficial to the species but not necessarily for the individual?

Give an example of a metal which

  (i) is a liquid at room temperature.
  (ii) can be easily cut with a knife.
  (iii) is the best conductor of heat.
  (iv) is a poor conductor of heat.

How would you name the following compounds?

   (i)    CH₃  -- CH₂  -- Br

  (ii)

(iii) 

Write equations for the reactions of

   (i) iron with steam
   (ii) calcium and potassium with water.

Give any two ways in which non-biodegradable substances would affect the environment.

Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

On the basis of the issues raised in this chapter, what changes would you incorporate in your lifestyle in a move towards a sustainable use of our resources?

Where do plants get each of the raw materials required for photosynthesis?

How can you as an individual contribute or make a difference to the management of (a) forests and wildlife, (b) water resources and (c) coal and petroleum?

Can you suggest some changes in your school which would make it environment-friendly?

Answer the following :
(a) Which hormone is responsible for the changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?

What changes are observed in the uterus subsequent to implantation of young embryo?

If you could use any source of energy for heating your food, which one would you use and why?

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus.